1. Field of the invention
This invention relates in general to combines for harvesting grain, and in particular to an apparatus for maintaining the sieve of the combine in a level position while the combine is leaning sideways on a hillside.
2. Description of the Prior Art
Combines of the type concerned herein are large, self-propelled vehicles for cutting and threshing grain. A combine has a header which has a blade that will cut the crop. An auger mounted to the header delivers the crop up into a threshing chamber. The threshed grain falls onto a set of upper and lower sieves. The sieves are oscillated in longitudinal directions and have a large number of fingers. Air blows upward through the sieves. The sieves separate the grain from the chaff, with the grain falling through slots between the fingers into a collection area for transport upward to a bin. The chaff will be blown from the combine.
A combine works best while it is level. The grain will be evenly distributed across the sieves while the sieves are level. However, a large percentage of the tillable acreage in the United States has hillside grades and terraces. Often it is necessary to cut the hillsides and terraces in back and forth sweeps, with the combine leaning laterally. When the combine leans, grain will be distributed onto the sieves unequally. The grain will pile up on certain portions of the sieves. This reduces the effectiveness of the separation between the chaff and the threshed grain.
Hillside combines are available. These combines have complex levelling mechanisms that level the entire combine relative to the header. While workable, levelling the entire combine is expensive.
Another approach to preventing uneven distribution of grain on the sieves is to place longitudinal dividers in the grain distributing pan that distributes the grain onto the sieves. Still, grain can pile up on one side. Also, mechanisms to level the grain distributing pan or to level the sieves relative to the rest of the combine have been proposed in the patented art.